Suggest Treatment For Redness And Bumps On Arms And Cheeks In Baby

My 14 month old has had bright red and bumpy cheeks all day. There is also redness and bumps on his arms. We thought it was just an allergic reaction to sunscreen from yesterday or pizza sauce last night. However, his ears (front and behind) are now bright red and his forehead is too. He does not have a fever, but the redness is hot to the touch.